The present invention relates to stents, and more particularly to bifurcated stents and methods of making bifurcated stents for insertion within a branching vessel.
Stents are well known in the art. They are typically formed of a cylindrical metal mesh which can expand when pressure is internally applied. Alternatively, they can be formed of wire wrapped into a cylindrical shape or sheets of material formed into a cylindrical shape.
Stents are devices which are usually implanted within bodily conduits including the vascular system to reinforce collapsing, partially occluded, weakened, or abnormally dilated sections of the blood vessel. Stents also have been successfully implanted in other areas, e.g., the urinary tract or the bile duct to reinforce such bodily conduits.
U.S. Pat. No. 4,994,071 (MacGregor) discloses an expandable, bifurcating stent having a main cylindrical lattice formed from interconnected flexible wire. Two additional cylindrical lattices, having smaller diameters than the main lattice, are similarly constructed. The main lattice includes a flexible wire interconnecting the main lattice to one of the additional lattices. A second flexible wire interconnects the main lattice to the other additional lattice. The flexible wires form backbones that extend axially along the length of the main lattice and along each of the additional lattices. One disadvantage of this bifurcating stent is the complex nature of the interconnection of the flexible wires forming the backbones with the loop structure of each lattice.
The present invention solves these and other disadvantages of the prior art by providing bifurcated stents and methods of fabricating and deploying bifurcated stents having a stem portion and two leg portions.
In a first embodiment of the invention, a bifurcated stent is made by providing three sheets patterned to a desired pattern, wherein two sheets are substantially the same size and the third sheet is wider than either of the first two sheets. Each of the sheets is formed into tubes by turning up the longitudinal edges and forming a joint by welding. The larger sheet forms a tube that acts as the stem portion of the bifurcated stent and the other sheets form tubes which act as the leg portions of the bifurcated stent. The two leg portions are then joined to the stem portion to form the bifurcated stent.
In a second embodiment of the invention, the bifurcated stent is formed by preparing two stent sheets. For each sheet, the longitudinal edges of a portion of the sheet are turned up and secured to each other to form one of the two leg portions of the bifurcated stent. The remaining free edges of each of the two sheets are then joined to form the stem portion of the stent.
In a third embodiment, the bifurcated stent comprises first and second tubular portions. The first portion has a proximal end which forms the stem portion and a distal end which forms one of the leg portions of the bifurcated stent. A branch aperture is disposed between the proximal end and the distal end of the first portion. The second portion is introduced into the longitudinal bore of the stem portion of the first portion and is advanced through the branch aperture so that it protrudes beyond the branch aperture to form a second leg. When the second portion is expanded, the proximal end of the second portion engages the material defining the branch aperture so as to secure the second leg in the desired position. It is an object of this invention to provide a method of making a bifurcated stent, comprising the steps of: a) preparing a first sheet having a first edge, a second edge, a third edge, and a fourth edge; b) preparing a second sheet having a first edge, a second edge, a third edge, and a fourth edge; c) preparing a third sheet having a first edge, a second edge, a third edge, and a fourth edge; d) attaching the second edge to the third edge of the first sheet to form a tubular first leg portion having a proximal end and a distal end; e) attaching the second edge to the third edge of the second sheet to form a tubular second leg portion having a proximal end and a distal end; f) attaching the second edge to the third edge of the third sheet to form a tubular stem portion having a proximal end and a distal end; and g) attaching the proximal end of the first leg portion and the proximal end of the second leg portion to the distal end of the stem portion.
It is another object of this invention to provide a method of making a bifurcated stent, comprising the steps of a) preparing a first sheet having a proximal end and a distal end; b) deforming the distal end of the first sheet to form a first leg and deforming the proximal end of the first sheet to form a first stem half; c) preparing a second sheet having a proximal end and a distal end; d) deforming the distal end of the second sheet to form a second leg and deforming the proximal end of the second sheet to form a second stem half; and e) joining the first stem half to the second stem half to form a stem.
It is yet another object of this invention to provide a method of making a bifurcated stent comprising the steps of a) preparing a first expandable tubular member having a proximal end and a distal end and a longitudinal bore therethrough, the first tubular member provided with a branch aperture disposed between said proximal end and the distal end, the branch aperture communicating with said longitudinal bore and the aperture sized and adapted to receive and secure a second expandable tubular member; b) delivering the first expandable tubular member to a bifurcated vessel having a first lumen and a second lumen so that the first expandable member is disposed within the first lumen and the branch aperture communicates with the second lumen; c) expanding the first expandable member in an amount sufficient to secure the first expandable member in the first lumen; d) preparing a second expandable tubular member having a proximal end and a distal end and having longitudinal bore therethrough; e) widening the branch aperture; f) delivering the second expandable tubular member into the branch aperture so that the distal end of the second expandable tubular member is disposed within the second lumen and the proximal end of the second expandable tubular member is disposed within the longitudinal bore of the first longitudinal member; and g) expanding the second expandable tubular member in an amount sufficient to secure the second expandable tubular member within the second lumen and within said branch aperture.
It is still another object of this invention to provide a method of making a bifurcated stent comprising the steps of:
a) preparing a sheet having a proximal end, a distal end, a longitudinal axis, and a circumferential axis, the sheet provided with:
a first side having a proximal portion having a proximal end and a distal end and a distal portion having a proximal end and a distal end;
a second side having a proximal end and a distal end, the second side disposed between the proximal end of the sheet and the distal end of the sheet;
a third side having a proximal end and a distal end, the third side disposed between the distal end of the second side and the distal end of the sheet;
a fourth side disposed between the proximal end of the proximal portion of the first side and the proximal end of the second side;
a fifth side disposed between the distal end of the distal portion of the first side and the distal end of the third side, the fifth side having a length that is shorter than the length of the fourth side; and
a sixth side disposed between the second side and the third side;
b) attaching the second side to the proximal portion of the first side and attaching the third side to the distal portion of the first side to form a first expandable tubular member having a longitudinal bore defining a longitudinal axis, the fourth side defining a proximal stent aperture communicating with the longitudinal bore, the fifth side defining a distal stent aperture communicating with the longitudinal bore, and the sixth side and the proximal end of the third side and the proximal end of the distal portion of the first side defining a side branch aperture communicating with the longitudinal bore and sized and adapted to receive and secure a second expandable tubular member;
c) delivering the first expandable tubular member to a bifurcated vessel having a first lumen and a second lumen so that the first expandable tubular member is disposed within the first lumen and the branch aperture communicates with the second lumen;
d) expanding the first expandable tubular member in an amount sufficient to secure the first expandable tubular member in the first lumen;
e) preparing a second expandable tubular member having a proximal end and a distal end and having longitudinal bore therethrough;
f) delivering the second expandable tubular member into the branch aperture of the first tubular member so that the distal end of the second expandable tubular member is disposed within the second lumen and the proximal end of the second expandable tubular member is disposed within the longitudinal bore of the first tubular member; and
g) expanding the second expandable tubular member in an amount sufficient to secure the second expandable tubular member within the second lumen and within the branch aperture.
It is yet another object of this invention to provide a bifurcated stent comprising:
a) a first tubular member having a proximal end and a distal end and a longitudinal bore therethrough defining a longitudinal axis, the first tubular member comprised of a sheet having a proximal end, a distal end, a longitudinal axis, and a circumferential axis, the sheet provided with:
a first side having a proximal portion having a proximal end and a distal end and a distal portion having a proximal end and a distal end;
a second side having a proximal end and a distal end, the second side disposed between the proximal end of the sheet and the distal end of the sheet;
a third side having a proximal end and a distal end, the third side disposed between the distal end of the second side and the distal end of the sheet;
a fourth side disposed between the proximal end of the proximal portion of the first side and the proximal end of the second side;
a fifth side disposed between the distal end of the distal portion of the first side and the distal end of the third side, the fifth side having a length that is shorter than the length of the fourth side; and
a sixth side disposed between the second side and the third side;
b) means for attaching the second side to the proximal portion of the first side and the third side to the distal portion of the first side so that the fourth side defines a proximal stent aperture communicating with the longitudinal bore, the fifth side defines a distal stent aperture communicating with the longitudinal bore, and the sixth side and the proximal end of the third side and the proximal end of the distal portion of the first side define a side branch aperture communicating with the longitudinal bore and sized and adapted to receive and secure a second tubular member; and
c) a second tubular member having a proximal end and a distal end and having longitudinal bore therethrough, the second tubular member disposed within the branch aperture so that the proximal end of the second tubular member is disposed within the longitudinal bore of the first tubular member.
It is a further object of this invention to provide a method of making a bifurcated stent comprising the steps of:
a) cutting a proximal member from a first expandable tube having a first cross-sectional diameter, the proximal member having a proximal end and a distal end and a longitudinal bore therethrough;
b) cutting a distal member from a second expandable tube having a second cross-sectional diameter smaller than the first diameter of the first tube, the distal member having a proximal end and a distal end and a longitudinal bore therethrough;
c) attaching a portion of the distal end of the proximal member to a portion of the proximal end of the distal member so that the longitudinal bore of the proximal member is in fluid communication with the longitudinal bore of the distal member to form a first expandable tubular member having a proximal end and a distal end and a longitudinal bore therethrough, the unattached portion of the distal end of the proximal member and the unattached portion of the proximal end of the distal member defining a side branch aperture communicating with the longitudinal bore of the first tubular member and sized and adapted to receive and secure a second expandable tubular member;
c) delivering the first expandable tubular member to a bifurcated vessel having a first lumen and a second lumen so that the first expandable tubular member is disposed within the first lumen and the branch aperture communicates with the second lumen;
d) expanding the first expandable tubular member in an amount sufficient to secure the first expandable tubular member in the first lumen;
e) preparing a second expandable tubular member having a proximal end and a distal end and having longitudinal bore therethrough;
f) delivering the second expandable tubular member into the branch aperture of the first tubular member so that the distal end of the second expandable tubular member is disposed within the second lumen and the proximal end of the second expandable tubular member is disposed within the longitudinal bore of the first tubular member; and
g) expanding the second expandable tubular member in an amount sufficient to secure the second tubular member within the second lumen and within the branch aperture.
It is yet a further object of this invention to provide a bifurcated stent comprising:
a) a first tubular member having a proximal end and a distal end and a longitudinal bore therethrough, the first tubular member comprised of a proximal member and a distal member, the proximal member having a first cross-sectional diameter, a proximal end and a distal end and a longitudinal bore therethrough, and the distal member having a second cross-sectional diameter smaller than the first diameter, a proximal end and a distal end and a longitudinal bore therethrough;
b) means for attaching a portion of the distal end of the proximal member to a portion of the proximal end of the distal member so that the longitudinal bore of the proximal member is in fluid communication with the longitudinal bore of the distal member to form the first tubular member, the unattached portion of the distal end of the proximal member and the unattached portion of the proximal end of the distal member defining a side branch aperture communicating with the longitudinal bore of the first tubular member and sized and adapted to receive and secure a second expandable tubular member; and
c) a second tubular member having a proximal end and a distal end and having longitudinal bore therethrough, the second tubular member disposed and secured within the branch aperture so that the proximal end of the second tubular member is disposed within the longitudinal bore of the first tubular member.